C13K—SACCHARIDES, OTHER THAN SUCROSE, OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DI-, OLIGO- OR POLYSACCHARIDES

C13K13/00—Sugars not otherwise provided for in this class

C—CHEMISTRY; METALLURGY

C13—SUGAR INDUSTRY

C13K—SACCHARIDES, OTHER THAN SUCROSE, OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DI-, OLIGO- OR POLYSACCHARIDES

C13K13/00—Sugars not otherwise provided for in this class

C13K13/002—Xylose

C—CHEMISTRY; METALLURGY

C13—SUGAR INDUSTRY

C13K—SACCHARIDES, OTHER THAN SUCROSE, OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DI-, OLIGO- OR POLYSACCHARIDES

C13K13/00—Sugars not otherwise provided for in this class

C13K13/007—Separation of sugars provided for in subclass C13K

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE

Y02E50/00—Technologies for the production of fuel of non-fossil origin

Y02E50/10—Biofuels

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE

Y02E50/00—Technologies for the production of fuel of non-fossil origin

Y02E50/10—Biofuels

Y02E50/16—Cellulosic bio-ethanol

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE

Y02E50/00—Technologies for the production of fuel of non-fossil origin

Y02E50/10—Biofuels

Y02E50/17—Grain bio-ethanol

Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE

Y02E50/00—Technologies for the production of fuel of non-fossil origin

Y02E50/30—Fuel from waste

Abstract

Non-food plant biomass is subjected to hot-water extraction in a pressurized vessel at an elevated temperature up to about 250° C and at a pH below about 7,0, to yield an aqueous extract containing hemicellulosic components, other wood-derived compounds, and a lignocellulosic residue, The separated aqueous extract or liquor is purified and concentrated through a multi-step process producing fermentable sugars. At each stage, inhibitory chemicals such as acetic acid, lignin, and furfural are separated and eventually recovered as commercial chemicals. The lignocellulosic residue may be further processed, as a material with enhanced resistance to sorption of water, for manufacture of improved: pulp and paper, construction materials, pellet fuel, and/or other useful products.

Description

Biorefinery Process for Extraction, Separation and Recovery of Fermentable Saccharides, Other Useful Compounds* and Yield of Improved LignoceUu osic Material from Plant Biomass

This application claims the benefit of the filing date of U.S. Provisional patent application Serial No. 61/264,901 filed on November 30, 2009 and U.S. patent application Seriai No. 12/850 662 filed on August 5, 2010.

TECHNICAL FIELD

The biorefinery process described hereafter can be set out concisely as the hot water 'extraction of non-food plant biomass (lignocellulosic material) for separation and recovery of cellulose, hemieelluSose, and associated compounds to be used for, or in the production o fuels, chemicals, structural materials, and other useful plant-based products.

BACKGROUND ART

The present invention involves a biorefinery process for pressure cooking woody or fibrous biomass (i.e.. non-food plant biomass such, as wood chips, plant stubble, food processing waste or other sources) in water to yield fermentable- saccharides, commercial chemicals, and other useful lignocellulosic derivatives, and also to yield woody or fibrous solids that are significantly improved for manufacture of pulp and paper, fuel pellets, fiberboard, and other' useful products.

Variou processes have been proposed for recovery of purified chemical compounds, from plant biomass, e.g., wood, chips or agricultural residues. Typically these fall into three categories: chemical hvdroJvsis. enzymatic bydroivsis. or hvdrothermal hvdrolvsis in combination with a chemical and/or enzymatic treatment, The general goal of these processes is depolymerization of cellulose (the structural portion of the biomass) into fermentable sugars and other biomass component chemicals, and/or directly targeting the end-product of etlianoi.

Chemical hydrolysis relies on using (primarily) an acidic (i.e.. low pH) or (less frequently) an alkaline (i.e., high-pH) solution to break down the structure of the biomass, and/or extract component chemicals from the fibrous or chipped plant material. For example, Lightner Published Application US 2003/0154975 discusses a method of hydrolyzing biomass, to produce a sugar phase and an aqueous acidic solution phase. The process involves removing sugars from a hydrolysate. The hydrolysate is formed into a phase containing sugars and a phase containing concentrated acid. The separated sugar phase may be subjected to additional processing. Similarly, O'Connor et al. Published Application US 2009/01.76.286, foody et al. Published Application US 2009/0023187, Zhang Published Application US 2009 0229599, forget Patent No, LIS 6,228,177, and I'sao et ah Patent No. US 4,281 ,063 treat lignocellulosic biomass with an acid solution for varying temperatures and times.

Enzymatic depolymerization systems are generally deployed in conjunction with, or following, hydrothermal fiberization (steam explosion) or physical comminution (grinding) of lianoeeilulosic biomass. Ahring et al. U.S. Pat.. 6.555.350. and Ahring et al. Published
Application US 2009/01.7867! present a process for converting Hgnocelluiosie biomass to ethanoi while utilizing, only a low volume of clean water. Brink U.S. Pat. 5,628,830 enzyma ically treats finely ground Hgnocdlulosic biomass to disassemble cellulose into its component glucose sugars for fermentation to ethanol, Noriyuki et al. Japan Publication number 207-074992, and Japan Publication number 2007-074993 utilize a combination of enzymatic and hydrothermal/pefoxide-aided treatment for the purpose of saccharifying cellulose. Lynd et al U.S. Pat. 5258,293 provide an improvement to "Direct Microbial Conversion" combined with "Simultaneous Saecharification and Fermentation" in which a single microbial system produces a cellulose disassembly enzyme, and subsequently also produces ethanoi as a fementation product in a single bioreactor at high, volumetric productivit rates.

Hydrotliermal only treatments are presented by Schmidt et al. VS. Pat. 6,692,578 wherein corn fiber is heated in water to 1 10° C to separate and Iwdroiyze hemiceliuSose into monosaccharides. Dahlman Published International Application WO .2009/068525 utilizes wood hydrolysis, subjecting the wood to an aqueous hydrotherma! treatment for hydrolyzmg and saccharifying the cellulose contained in the biomass, and separating it into fractions for production of polymers and monomers. L.ignin is decomposed by enzyme action, and removed.

None of these previously proposed systems specifically address removal of acetic acid or other fermentation inhib ve chemicals from the extraetant liquor, and eonsequenily it is not likely that the processes isolate highly fermentable sugars from the Hgnocdlulosic material. Similarly, none of the previously proposed systems separate and recover the wide array of commercially valuable, naturally occurring chemicals contained in Hgnocdlulosic biomass. Lastly, these prior systems tend to attack, the structural component of the woody biomass, and therefore none of these prior systems recognize the manufacturing benefits available from keeping the .fibrous solids largel intact during and after removal of the hemicellulosic and other wood-derived compounds.
msci im OF THE INVENTION

It is an object of this invention to provide a technique that yields a wide variety of useful products from !ignocel osic biomass, including fermentable sugars and lo -hydrophilic solids, while avoiding limitations of the prior art.

it is another object to provide a. process in which non-food plant biomass can be readily treated to yield these useful products, while at the same time separating and recovering Inh iive chemicals which diffuse into the liquor from the woody biomass during the extraction process. Since the inhibitory chemicals are themselves valuable in commerce, separation and recovery of these materials increases diversity of the overall output product stream, and thus increases the probability of commercial -economic viability.

According to one aspect of the present invention, useful biochemical can be coaxed from non-food plant biomass, with a hot-water extraction technique that is carried out by contacting a charge of non-ibod plant biomass material, with water (with or without additional process enhancing compounds or materials), in a pressurized vessel at an elevated temperature up to. about 250° C and at a pH belo about. 7.0, to yield an aqueous (extract solution) mixture of useful chemicals including long-chain saccharides (sugars), acetic acid, methanol, formic acid, furfural, and ligni.n, while leaving the structural (cellulose and lignin) portion of the ligrtoee!infcisie material largely intact, in mixture these chemicals are not useful, so the extract solution must be further processed to purity and concentrate these naturally occurring iignoceilulosic-based components and compounds. Toward this objective, the aqueous extract is sundered (by centrifugation, filtration, solvent extraction, floceuJation, evaporation, and/or membrane separation) to begin isolating sugars in a concentrated sugar stream, apart .from the other hemiceliulose and wood-derived compounds which are channeled into a "permeate*' stream.

Then, along one sub-path of the process, the concentrated, long-chain sugars are hydrolyzed (cleaved) into monomer/dimer (short-chain) saccharides, i.e., simple sugars such as xylose and glucose. This hydrolysis may be accomplished, using enzyme, acid, solid acid, and/or heat treatments followed by p l correction as necessary. During sugar hydrolysis, add tional inhibitory components (e.g., acetic acid, methanol, etc.) are released or formed (e.g. furfural) as the long-chain sugars break apart into short-chain or single sugar molecules. At this stage the hydrolyzed sugar concentrate solution, may or may not be diluted by a ratio of between 2:1 and 40:1. In either case the hydrolyzed sugar solution is then further processed to remove
the newly released (during hydrolysis) inhibitors to produce a purified short-chain sugar solution sufficiently free of inhibitor compounds as to be readily fermentable.

According to another aspect of the invention, the technique of improving non-food, iigooceUulosic components for manufacture of wood products can be earned out beginning with hoi-water extraction involving the contactings of a charge of the non-food plant biomass materia! with water (with or without additional process enhancing compounds or materials), in a pressurized vessel at an elevated temperature up to about 250° C and at a pH below about 7.0, to yield an aqueous extract containing hemice!luiosic components, other wood-derived compounds, and a lignocellulosic residue. The pressure vessel contents are discharged, and the llgnocellulosic residue is separated front the aqueous extract.

Once separated from the extract liquor, the post-cook, residue is in the form of a ceHulosic solid material significantly reduced in content of !ong-ehaio, non-eellulose, sugar and other hydrophilic components. The HgnoeeHulosic material, with reduced hydrophilic components, is more resistant to absorption or adsorption (generally, sorption) of water, and possesses higher Bui content per unit of weight. With reduced hemfceSf ulose content, the extracted residue pulps and bleaches with greater speed and less material cost, and therefore constitutes and improved raw materia! for the manufacture of paper products. Additionally, the residue can be used to produce reduced- ydrophilic, traditional wood products such fiberboard or fuel pellets where resistance to water reduces product deterioration in high humidity environments. And lastly, the increased Btu content coupled with moisture resistance makes the resulting fuel pellets an improved, renewable, alternative heating fuel
BRIEF .DESCRIPTION OF THE DRAWING (FIGURE I)

The right-band side of the Drawing (Figure 1) is a process flow chart for explaining the 'extraction process producing concentrates and permeates from which useful lignocellulosic- sugar feedstocks, and other Hgnocellulosic-derived compounds are separated and recovered.

The left side of ike 'Drawing (Figure 1 ) depicts a process flow through which the solid component of the extracted, lignocellulosic material, with reduced hydrophilicity, is forwarded for use as fuel, or for further manufacture into wood products, wood derivatives, or other useful lignocellulosic materials.

BEST MODE FOR CARRYING ODT THE INVENTION

The generalized flow of the extraction process depicted in. the Drawing (Figure 1 ) can be described as follows.

The first step is the receiving and pre-processing of available .non-food Hgnoceliulosic feedstock [10], which may include, e.g., wood chips, straw, or any other plant matter. There is a gross screening process in which oversized .materials (large chunks of wood) and contaminates (stones, soil, etc.) are selected and removed. This may include organic debris, detritus, as well as some Hgnoceliulosic material. This is followed by a fine screening, in which undersized particles, or fines, including contaminates, such as sand, soil or the like, are separated and removed. This may also include organic debris, detritus, and lignoeeliulosie material The remaining Hgnoceliulosic material, may be triturated (e.g., by chipping, tub grinding, hammer milling, or other available comminuting procedure) to reduce the feedstock to preferred size (comparable to commercial, woodehips for pulping or smaller) and condition for further handling and processing. Magnetic screening and separation is applied at this time to remove any tramp metals that may be present in the lignoeeliulosie stream.

Then, a hot water extraction process [I I ] is applied to the prepared non-food lignoeeliulosie material, which is effective for a mass removal, most preferably between about ten percent and thirty-five percent. This may be done fay batch processing, continuous processing, or semi-continuous processing. The hot water extraction process involves contacting the charge of prepared non-food lignoeeliulosie material with water (with or without small amounts of acetic acid, furfural, or other process enhancing compounds materials), in a pressurized vessel, at a temperature in a range between 20° C and about 250° C, and at a low H, i.e., in a range of about 0,5 to 6,9, for a period of time of between one second to 200 hours, so that, an aqueous extract (or liquor) containing solu.bil.ized components of the Hgnoceliulosic material is obtained. The remaining non-food lignoeeliulosie material [12] (i.e., fibrous material) is separated from the liquor or extract [13], and each may be further processed as discussed below.

The separated aqueous extract [13] is processed in a series of stages to isolate and recover valuable hemiceltiilosic, and other Hgnoceliulosic derived, compounds; this is shown on the ri ght-hand branch of the Dra wing.

In the next stage [16], a concentrated, water-based solution of complex and simple saccharides [17] is created by further filtering the aqueous extract stream to remove non-sugar compounds, many of which are inhibitory to fermentation, into a peraieate solution [18]. This partitioning/concentration [16] can. be carried out via membrane separation, and/or evaporation, and/or solvent extraction, and/or by any combination of these processes.

In the next stage [20], the acid hydroiyzed sugar solution may be pH-corrected (with an alkali, or base) as necessary, before being further treated to isolate and recover commercially valuable chemicals [21 and 22]. This isolation and recovery step may collectively involve cenirifugation, and/or membrane separation, and/or sedimentation, and/or filtration, which serve to remove aromatic products [21 ] from die hydroiyzed sugar solution. Further product separation [22] is necessary for final removal of inhibitory compounds, either by diaflltration using a single- or multi-stage- membrane with counter-current or n n-eoimier-current flow, and/or solvent separation using selective chemical separation Involving water-immiscible solvents. As output streams om the product separation [22], the inhibitory chemical solution is then conveyed [24] to a recovery phase [I S], while the remaining aqueous concentrate now consists mainly of fermentable, monomeric sugars [23] of the types mentioned above. There can be successive stages of hydrolysis, concentration, and separation to increase the yield of useful sugars from the feedstock. The pH correction shown at [20] may be conducted after the product recover stages [21] and/or [22],

In the first purification, step [1.4], larger aromatic and oligomeri.c molecules are removed and recovered as products [15]. in subsequent purification steps [16, 1 , 20, and 22], organic chemicals, such as acetic acid and other inhibitory compounds which have been, solubiiized in the aqueous extract, are separated so that the complex saccharides can be further hydroiyzed and purified to yield fermentable, short-chai sugars. Hie separated inhibitory materials [18 and 24] are combined, and processed as discussed next.

As shown at the right hand sub-branch, the permeate solution of inhibitory products isolated in previous steps [1.6 and 22] is processed [25] to separate and recover component commercial chemicals, e.g., acetic acid, formic acid, methanol, furfural and water. This
separation and recovery may be achieved by solvent extraction, and/or distillation, and/or membrane separation, and/or pervaporation, and/or crystallization, and/or any combination of these, The isolated compounds are available for commercial sale as platform chemicals [1 5 and 26],

Again referring to the Drawing, the initial steps [10] and [1 1] lead to two product streams: the previously discussed aqueous extract [13], as well as to the extracted ligooceSlulosic materia! [ 12]. The residual fibrous biomass material with the extracted materials removed [12], may be forwarded as raw material [30] for use as fuel, or for manufacture of wood products and/or wood derivatives. As previously described, the process begins with the autoeatalytic, hot-water separation of heniiceiluiosi.c compounds from the lignoceUulosic biomass. The process generally includes the receiving and pre-processing of lignocellulosk material as described above [1.0 , .followed by cooking the lignoeellislosic material in hot water [1 1 ]. The liquor or a ueous extract [13] is removed from the cooked biomass solids [12]. The cooking process removes a significant portion (typically 23%) of the hydrophiJi or water sorptive chemicals fr m: the lignocellulosk material The residual biomass solids are thus sia fkantlv less dense than the starting feedstock, materials, and are also characterized by significantly reduced hydrophilicity (i.e., less attractive to water). Products made from this reduced hydrophilic material are less prone to water sorption from the environment, and thus will be less prone to softening from contact with water, and less prone to rot or deterioration, in addition, because this material equilibrates at very low water content and is relatively free from ash producing inorganic elements and hernieelluiose compounds, it can serve as an increased Bin-content fuel in the form of chips or pellets [31 ], In addition to fuel, other more valuable end-uses for the extracted lignocellulosk material are: pul [12], fiber-hoard [33], or as a bio-conversion feedstock [34].

in an. embodiment of the process, the wood-yard supplies woodchip feedstock and handles oversized material, dust and tramp metals. Screening, and magnetic separation can he used for this preparatory phase. Favorably, storage for up to forty-live days worth of green wood will be available to maintain feedstock supply to the extraction operation. Self-dumping trucks deliver wood chips to the facility, and the wood is automatically handled by conveyor and/or mobile equipment (skid-steer, front loader, etc.).

in another embodiment, the extraction of lignoeelSulosic materials via water-based .autohydrolysis removes from 10 percent up to 35 percent (typicall 23%) of the mass of the lignoceUulosic materials in a continuous, semi-continuous, or batch process peration. The
E H ] iignoceil'uiosic materials are contacted with water at a temperature in the range of 20° C to 250° C and a pH in the range between 0.5 and 6.9 for a period of at least one second and up to about 200 hours, wherein an aqueous extract (or liquor) and extracted lignocelhUosic materials are obtained.

A heated pressure vessel is used for extraction, and a two-stage washing system can be included to provide improved capture of extracted material. Chip feed and removal, in combination with liquid handling equipment are employed to fill and evacuate the pressure vessel A heat exchanger is used to cool the extract or liquor, and to recover and recycle heat hack to the hot. water extraction pressure vessel. A holding tank stores the extract for downstream processing. A. transfer pump and bag filter may be used to transfer and clean the extract in preparation for first-stage filtration.

In another embodiment following hot water extraction and coarse materials removal., first-stage filtration operates as a Hgnin and high molecular weight removal system for improving the efficiency of further extract solution downstream processing. During first-stage filtration, high molecular weight, and suspended materials are dissociated from the extract solution fay one or more of; .sedimentation, eentrifugation, filtration, hydro-cyclone, and/or fioeeulation. The cleaned extract solution from this step is cooled as necessary for the next processing stage.

In another embodiment following first-stage filtration, the next stage further refines the cleaned extract solution by separating monomerie and oUgomerie sugars from inhibitory compounds such as acetic acid and furfura!. This partitioning step can be accomplished by membrane separation, evaporation, and/or solvent extraction. The output products from this stage consist of a concentrated sugar solution (primarily oligomers with some monomers and dimers), and a permeate solution containing iiiiiibitorv and other compounds,. Both solutions will be .further refined and/or transformed into commercial chemicals.

In another embodiment acid hydrolysis is performed on the concentrated sugar solution t break apart long-chain sugar polymers to mon melic or dimeric form by one or more of enzyme, acid, solid acid, and/or heat treatments. The addition of acid causes precipitation of aromatic materials and certain, suspended solids from the concentrated sugar solution; these solids are later recovered. Then, application of heat to the hydrolysis process releases further materials into suspension. Following hydrolysis these newly-released solids are removed and recovered from solution by centrifugation, filtration, membrane separation, and/o hydro- cyclone. The sol ution may then be pH-eorrecied as needed for farther processing.
in another embodiment following acid hydrolysis* additional fermentation inhibitors such as acetic acid and furfural are released and must be removed from the sugar stream, t his purification ste may occur before or after pH correction, and is accomplished using single or multi-stage membrane separation, either with counter-current flow or non-countercurrent flow, and/or solvent separation (le., selective chemical separation with water immiscible solvents)* In the ease of the membrane separation, called diafiltration, two new streams are produced: a short-chain sugar solution containing xylose, .niannose, arabinose, rhamnose. galactose, and glucose (5 and 6-carbo.u sugars), and a new permeate solution containing chemicals such as acetic acid, formic acid, furfural, and methanol. The- sugar stream, now significantly reduced in content of inhibitory substances, may be converted by fermentation into such products as butano!, acetone, ethanoi, et al. If pH correction has not been performed before separation of the inhibitory products, it will be performed before fermentation, and the target: pH will be determined to satisfy desired conditions for the fermentation organism and corresponding end product.

in another embodiment, water from both the sugar and permeate streams may be recovered by evaporation-condensation and/or membrane separation and/or steam stripping and/or air stripping.

While the invention has been described with reference to specific examples and embodiments, the invention is not to be limited to those embodiments, but the scope of the invention is to be ascertained from the appended claims.

Claims

What is claimed is:

\ , Process of extraction of useful bioehemicals from a non-food plant biomass, the process comprising:

a) hot-water extraction carried out by contacting a charge of the non-food plant biomass material with water, in a pressurized vessel at an elevated temperature up to about 250,i C and at a pH below about 7.0, to yield an aqueous extract containing heinieellu sie components and other Hgnocellulosie derived compounds and a Hgnocellulosie residue;

b) separating the Hgnocellulosie residue and other coarse materials from the aqueous extract;

c) processing the aqueous extract to remove larger aromatic and oligomeric molecules; d) deriving a more pure, concentrated sugar solution from the aqueous extract remaining alter step c) by sundering of oligomeric sugars into a concentrated sugar stream and fermentation inhibitory compounds Into a permeate stream:

a) hot-water extraction carried out by contacting a charge of the non-food plant biomass material with water, in a pressurized vessel at an elevated temperature up to about 250° C and at a pH below about 7.0, to yield an aqueous extract containing hemicel.iulosic components and a HgnocelluJosic residue;

b) separating the aqueous extract from, the lignocellulosic residue:

c) further processing the separated aqueous extract: and

d) processing the lignocellulosic residue to yield useful products.

10. The process of Claim 9 wherein the lignocellulosic residue of step d) is significantly reduced in content of hydrophitic components.

11. The process of Claim 9, further comprising processing the residue of step d) to produce a structural building .material.

12. The process of Claim 9, further comprising processing the residue of ste d) into wood pulp.

13. The process of Claim 9, further comprising processing the residue of step d) into fuel pellets.